Broadband data communications networks, such as WiMAX, provides wireless data in a variety of ways, from point-to-point to full mobile cellular type access. WiMAX stands for Worldwide Interoperability for Microwave Access, and is based on the IEEE 802.16 standard.
WiMAX may be used for connecting Wi-Fi hotspots with other parts of the Internet, and for providing a wireless alternative to cable and DSL for last mile broadband access. WiMAX is a possible replacement for cellular phone technologies such as GSM and CDMA, or can be used as an overlay to increase capacity. It has also been considered as a wireless backhaul technology for 2G, 3G, and 4G networks in both developed and developing nations. Backhaul for remote cellular operations is typically provided via satellite, and in urban areas via one or more T1 connections.
A WiMAX communications network uses access service network gateways (ASN GWs) for setting up connections between base stations and mobile communications devices. Each access gateway is part of an access service network (ASN), which is typically owned by a network access provider (NAP). Each ASN communicates with a connectivity service network (CSN), which is typically owned by a network service provider (NSP). The CSN transfers data to and receives data from a data network, such as the Internet.
The CSN may operate as the home agent (HA) and may also provide the authentication, authorization and accounting (AAA) functions for the mobile communications devices. The AAA functions may be stored in an AAA server. The CSN may also directly communicate with a mobile communications device. The CSN may be considered the home CSN, and communicates with a visited CSN for internetworking therebetween, as readily appreciated by those skilled in the art.
Communications between an access gateway and the base stations need highly reliable connections therebetween. However, this is not always the case. If such a connection is lost, then basic functions such establishing user device connectivity, maintaining user device connectivity, and providing handoff to another base station are not available.
U.S. Pat. No. 7,317,707 to Rajkumar et al. discloses a method for seamless session transfer of a mobile communications device within a WiMAX communications network. In the method, a source base station sends first information to a target base station. The first information indicates a sequence number of a first data unit in a sequence of data units undelivered to the mobile station by the source base station. The source base station also sends the target base station second information. The second information indicates data units, after the first undelivered data unit in the sequence, that have been delivered to the mobile station by the source base station. The second information may further indicate portions of the first undelivered data unit that have been delivered to the mobile station by the source base station.
U.S. Pat. No. 7,317,708 to Moon et al. discloses a method and apparatus for providing indoor and outdoor wireless access in a broadband data communications network, such as a WiMAX communications network. A mobile WiMAX bridge serves as an access point (AP) of a wireless local area network (WLAN) (e.g., a wireless fidelity (WiFi) system or Mobile WiMAX system) for an indoor network, and simultaneously serves as an access point (AP) of a mobile WiMAX system for an outdoor network.
There is still a need to provide reliable communications between an access gateway and base stations. If reliable communications is not available, then basic functions for the mobile communications devices operating within a broadband data communications network are not available.